This part of IEC 61788 covers a test method for the determination of the residual resistance ratio (RRR) of composite superconductors comprised of Nb-Ti filaments and Cu, Cu-Ni or Cu/Cu-Ni matrix. This method is intended for use with superconductors that have a monolithic structure with rectangular or round cross-section, RRR less than 350, and cross-sectional area less than 3 mm2. All measurements are done without an applied magnetic field. The method described in the body of this standard is the “reference” method and optional acquisition methods are outlined in Clause A.3.